Oil switch



L. MAGRINI July 29, 1930.

OIL SWITCH Filed Dec. 23, 1926 Patented July 29, 1 930 LUIGI HAGRILITI, Ol' BERGAMO, ITALY OIL SWITCH Application filed December 88, 1988, Serial lo. 156,873, and in Germany l'ebrnary 1B, 1988'.

This invention relates to improvements in oil switches or lnterrupters.

O11 switches are known in whlch differently distributed cavities are arranged and com- Y municate with the interior of a reservoir, thus allowing the gases produced b the decomposition of the oil to expand. hese expansion chambers constitute sometimes a separate space above the oil surface to which the gases of decomposition are led.

Switches are alsol known in which the said gases are led to the exterior by suitable communications and, again, arrangements areknown which pass a current of oil to the part where the arc forms, for the purpose of quenching the latter. p p

Heretofore, however, these three features have not been embodied in a single switch, and the practical embodiments hitherto proposed of each of the three features have actually been of a nature such as to exclude the other two. 4

This invention has for its object to provide an oil switch in which the three above mentioned features exist together, and it is characterized in that the movable contact or contacts of the switch are carried by a plunger -or piston which creates in its upward stroke a space, the volume of which increases proportionally to and simultaneously with the production of the gases of decomposition of the oil.

` Since the dimensions and the speed of disl v placement of the piston can be selected in such a way that the expansion space or chamber is always equal to or greater than the volume of gas produced by the decomposition of the oil, the pressure of the gas will never exceed that of the atmos here and consequently the pressure of t e gas will never unction to dls lace the piston, nor dischar e the gas. In act, these dimensions can calculated for the extreme case whenthe switch is opened under short-circuit. Consequently under more favourable circumstances, where the production of the s is less, a partial vacuum will be produced 1n the interior of thechamber of the switch and the gases will only be discharged to the exterior uring the descending stroke of the piston which will compress them in the upper art of the chamber of the switch above the evel of the oil. p

In the accompanying drawing, the single figure represents by way of example 'a vertical section of a device for carr ing out the invention and incorporating t e aforesaid three features.

The essential feature of this device is that the plunger or piston is hollow and filled with oil and is provided at its lower end with small openings which allow the oil to flow slowly into the reservoir as soon as the pivot is raised, in order to fill the said reservoir completely and consequently prevent the formation of an air space. A check valve is disposed in the gas outlet pipe to prevent the entrance of air into the reservoir.

A cylindrical body 1 fixed to the base 3 and to the cover 4 forms the reservoir 2 in which moves a plunger or piston 8. `The pisf ton is hollow and is provided with a rod 81 which is also hollow, the interiors of both the piston and rod being in communication with one another ,andwith the atmosphere through the end of the rod. The piston is provi ed with a contact 51, of which the corresponding contact 5 is carried b the base 3, and isalso rovided with smal openings 5" for the disc arge, of the oil. The cover 4 is rovided at its highest part with a pipe 41 or the discharge of the gases, which are led to the atmosphere by the pipe 4".

A non-return valve 16 of any known type prevents the entrance of air even when there is a partial vacuum within the reservoir.- A pipe 15 puts the interior 17 of the cylinder 18 in which is disposed thel rod 81 into communication with the outlet 4". T he c lin- Yder 18 forms a guide for the rod 81 an for the piston while allowing the oil contained inthe chamber 17 to descend tothe lower chamber 2.

The operation is believed to beapparent from the above descri tion. The principal feature is the use of t e hollow piston and rod and in the provision of the small openings 5 at the bottom of the iston. The

oil in the reservoir fills the cham ors 2, 41,4"

and 17 and the interiors-0f the Pisten and of the rod 81 up to the level A-A?. When the piston is raised rapidly it functions as a solid piston. If it is raised slowly or left in its upper position the oil issuing throu h the small openings 5" completely fills t e chambers of the apparatus. This arrangement, in cooperation with the non-return Valve 16, completely eliminates the formation of air spaces in the apparatus and consequential defects.

The shape and arrangement of the-various parts of the apparatus obviously can be varied according to necessity without departing from the scope of the invention.

Having now particularly described and ascertained the nature of my invention and in what manner the same is to be performed I declare that what I claim is:

1. In an oil switch, the combination of an oil reservoir, a contact within the reservoir fixed to the bottom thereof, a hollow piston movable vertically within the reservoir and having a plurality of ports at its lower end to enable oil to enter and fill the piston when the latter is lowered and to escape from the piston when raised, a hollow rod or stem connected to the piston and communicating with the interior thereof and with atmosphere, and a contact Ifixed to the lower end of the piston for coaction with the first. contact; said piston creating within the reservoir during its upward movement a gas space having at least the same volume as that of the gases produced by decomposition of the oil.

2. In an oil switch, the combination of an oil reservoir, a contact Within the reservoir fixed to the bottom thereof, a hollow piston movable vertically within the reservoir and having a plurality of ports at its lower end to enable oil to enter and lill the piston when the latter is lowered and to escape from the piston when raised, f a hollowrod or stem connected tothe piston and communicating with the interior thereof and with atmos phere, a contact fixed to the lower end of the piston for coaction with the first contact, an outlet pipe for the gases of decomposition of the oil having its mouth below the level of the oil when the switch is closed but uncovered when the oil level drops consequent on the upward movement' of the piston. and a lcheck valve in said outlet 'pipe for preventing,Y

l entrance of airinto the reservoir consequent on the' partial vacuum produced therein during -such.upwardmovement; sald piston cre- ?.itinigthn' the reservoirduring its said upward:movementl a'gasspace having' at 'least the same volume as that of the said l. I3v.. In. an foil switcln the-combination of .a reservoir provided'with a gas outlet and with an internal contactand filled with oil; and ba-piston having ports at litsbottom and provided 'with afcontact for"c operation with the le'SQiYOI'", 0I1taC.t. 1nd 'adapted to plunge ture.

' LUIGI MAGRINI.4 

